Log splitting has been going on as long as man has been burning wood for fire. Until recently, logs were either split by hand using an ax, or using a pneumatic or hydraulic log splitter. The earliest log splitters were single direction log splitters, where a log was placed near a wedge and a ram pushed the log against the wedge, thereby splitting the log. However, these log-splitting devices were slow, and were not amenable to production methods and quantities required because each log required a single stroke of the ram, and the ram needed to be returned to the original position. In the spirit of increasing production, in the recent history, bi-directional wood splitting devices were invented in order to speed up the log splitting procedure.
In the past, certain attempts were made to make a log-splitting device which included two splitting wedges with a hydraulic ram therebetween in order to utilize each stroke of the ram to split logs, in both directions. These bi-directional log-splitting devices did not meet with much success, because the forces of the hydraulic ram were greater in one direction than in the other. For instance, most of the devices known to the inventor have a capacity of nearly 20,000 pounds of force in one direction, while only 8,000 pounds of force may be exerted on the return stroke. This meant that the operator of the log-splitting device needed to carefully select the logs that he would be splitting in order to match the logs with the force being exerted in either direction. Needless to say, this is cumbersome and unwieldy.
Such an attempt was made by Joseph T. Butas, Jr., in the disclosure in his U.S. Pat. No. 3,974,867 issued Aug. 17, 1996, in which a log splitter for use in a high production environment utilizes a four-way, step knife blade at either end of a longitudinal stroke. Although this invention utilizes a self-centering circular ram connected to a two-way hydraulic cylinder, it is apparent that unequal forces are experienced between the extension and the return of the hydraulic stroke.
U.S. Pat. No. 4,351,377 issued Sep. 28, 1982, to Daniel L. Hamel discloses a bi-directional log splitter, although it uses a double-faced log-splitting wedge secured to the rail generally mid-way of the stroke motion of the log transporting bed. The log-splitting wedge is arranged to engage and split logs traveling within the bed.
U.S. Pat. No. 4,416,313 issued Nov. 22, 1983, to Richard E. Seeger discloses a double acting log splitter utilizing a carriage which is driven in opposite directions by an operating mechanism which includes a nut carried by the carriage for movement and a screw having one end fixed axially by and rotatably supported in bearings located at one end of the frame. A reversible drive motor is connected to the supported end of the screw for rotatably driving the screw in one direction or in its reverse. U.S. Pat. No. 4,423,759 issued Jan. 3, 1984, also issued to Richard E. Seeger, discloses an electrically powered log splitter, again with a reversible electric motor.
Lastly, U.S. Pat. No. 4,945,960 issued Aug. 7, 1990, to Christopher J. McCauley discloses a double action vertical wood splitter, with a removable double edged blade mounted on a elongated carriage which telescopically interacts with the frame resulting in a log splitter which can be used in either direction.
Therefore, it would be advantageous for an equal force bi-directional log splitter to be provided to increase the yield and production of the log splitting operation. It would also be an advantage to have this log splitter be small, convenient, and trailerable. It would be of special advantage if the cylinders were arranged to exert an equal lateral force, providing the same degree of compressibility in both directions.
It would furthermore be an advantage to utilize a double direction log splitter to increase production of split logs while exhibiting a minimal leverage effect on the log splitter itself. Further, it would be an even bigger advantage to include the use of a four-way knifed wedge with a double action equal force log splitter, whereby each log would be split into four pieces once the four-way star-shaped splitting head was compressed through a log.